On Jan. 25, actress and model Liberty Ross filed for divorce from her husband Rupert, six months after he’d been caught cheating with 22-year-old Kristen. It was during the filming of Snow White and the Huntsman, a movie starring Kristen that Rupert directed, in which they began their love affair.

And now, with R. Patz busy shooting his new film, The Rover, nearly eight thousand miles away in Australia, the Twilight star has reason to be concerned about leaving his once-unfaithful girlfriend behind.

“Rob’s friends are warning him that she cheated once, so what’s stopping her from doing it again?” a friend tells In Touch. “She’s desperate to hold on to [Rob] but she felt that way before — and she still cheated.”

According to a pal of the director, it would be Rupert, 41, who reaches out to Kristen— not the other way around.

“It wouldn’t surprise me at all if Kristen and Rupert got back in touch, and it would be Rupert who reached out,” he says. “He was infatuated with her.”

Rob might be worried about what Kristen is getting up to in L.A. while he’s half a world away, but the insider says that “with so many people watching her every move, if she hooks up with Rupert, he’ll find out about it.” And if that happens, “They’ll be done for good.”

Do you think Kristen would cheat again? Sound off in comments!

For more on Kristen and Rupert's temptations, pick up this week's issue of In Touch, on newsstands now.